Pallet



Feb. 18, 1969 J. E. HEFFERNAN 3,42

PALLET Filed Aug. 14, 1967 Fig. 2

F l'g 4 2O INVENTOR. F 1 9 3 Joseph E. Hlefferncn BY qvdymze ATTORNEY.

United States Patent a f 7 Claims ABSTRACT OF THE DISCLOSURE A pallet structure having a single horizontal support platform and leg support structure whose supporting flanges are connected in the plane of the platform and the legs depend therefrom.

This invention relates to a pallet structure of the type usable with fork lift trucks, and more particularly to a nestable light weight heavy-duty pallet.

Background of the invention The present nestable pallet is single faced and free standing of the leg supported type. It has a single vertical load supporting platform apertured at the leg supports to permit stacking or nesting.

Heretofore the most common types of nestable pallets have been made by forming molded paper and/or by molding a plastic platform integral with the leg structure. These common types of pallets are not capable of supporting heavy loads under adverse use conditions.

Single lfaced nestable pallets capable of carrying a heavy load have been suggested. One teaching suggests using a dual sheet metallic platform separated by a light weight honeycomb material. Another teaching suggests employing a specially formed shelf having truncated holes therein. In both teachings the leg structures are attached to the bottom exposed surface of the platform or shelf.

Summary of the invention Applicant has discovered that most loads applied to pallets are well distributed and that the limiting factor in weight support is the ability of the leg structure to support a load. Accordingly, there is provided a novel onepiece leg structure having maximum load carrying ability 'for its weight and cost.

Applicant has further discovered that most single faced nesta'ble pallets fail when any one leg collapses. These failures occur when the leg proper fails, the attachment flange bends and fails or the leg structure is detached from the platform by use or poor attachment, thus, increasing the load on the remaining leg structures. Accordingly, Applicant has provided an attachment structure within the supporting platform which overcomes the problems of the prior art by uniformly loading the leg portion of the leg structure and mechanically locking the leg structure to the platform.

Drawings FIG. 1 is a side view of a preferred embodiment pallet structure.

FIG. 2 is a plan view of the bottom surface of the upper structural supporting platform.

FIG. 3 is an enlarged partial section taken at lines 3-3 of FIG. 1.

FIG. 4 is an enlarged partial section of a preferred embodiment leg support structure.

Description of the preferred embodiment Pallet generally comprises an upper structural supporting platform 11, a lower platform 12 which serves 3,428,003 Patented Feb. 18, 1969 no structural supporting function, and a leg structure 13. The bottom surface of platform 11 is routed to form annular recesses 14 each having a bottom surface 15 and a vertical side 16. The bottom surface 15 of the recess 14 extends inwardly into the aperture 17.

Each leg structure 13 is formed from a single fiat sheet, preferably low carbon steel. Deep-drawing and power spinning are the preferred techniques as they flow the metal into the desired shape. Most pallets for use with fork lift trucks require approximately four inches clearance. The leg structure 13 comprises a flange 18, extending substantially horizontally outward from the top of the cup-shaped structure, a tapered leg 19 depending therefrom and a base 20 closing the small end of the leg.

The cup-shaped leg structure 13 is preferably made as light as possible for a given weight. Accordingly, in the process of manufacture the thickness II of flange 18 is made greater than the thickness t2 of the leg 19. The thickness of the base t3 is preferably not changed, and remains approximately the same as the flat blank from which the leg structure was made. The radius r1 is preferably made 5 to /2". Keeping the radius large has been found to avoid wrinkles which lead to stress concentrations and subsequent failures. Radius r2 is preferably made between A5" and the larger radius aids in ease of manufacture yet lessens the area of the diskshaped base 20 upon which the load ultimately bears. The included angle between the leg 19 and the flange 18 is preferably maintained at 104 to As an example of the advantage of the preferred novel leg structure 13, a fiat disk of .050" thickness was power spun into a truncated cone-shaped cup having a leg thickness t2 of .017", t1 and t3 remaining practically unchanged. The leg structure was four inches deep having a two inch diameter base and a :four inch diameter opening, the above radii r1 and r2 being held to their minimum. A series of tests proved that the leg structure would successfully support 1800 pounds. To further illustrate very high load carrying capacity, five such leg structures described above were placed in a routed laminated upper support platform 11, approximately 35 x 39", and loaded with a distributed load of 9000 pounds. The total weight of the pallet was only nine and one-half pounds (9 /2 1b.). A double faced pallet made of scrap or cheap lumber of the same area and carrying capacity will weight approximately fifty pounds (50 lb.). More than five of the pallets above described can be stored in the space occupied by the wooden double faced pallet.

A leg support structure 13, approximately .070" thick in the flange 18, may be reduced by approximately twothirds in the leg 19. Similar ratios of twenty to forty percent may be obtained through careful control employing deep-drawing techniques. However, when deep-drawing the leg structure it is necessary to increase the radii r1 and r2 to approximately /2" and /8, respectively.

In addition to controlling the thickness of the leg it has been found advantageous to hold the aperture 17 as small as possible and still allow nesting. As shown in FIG. 3, the edge of the platform 11 is extended to the intersection of the flange 18 and the leg 19, thus providing maximum area contact between the platform 11 and the flange 18 without interfering with the leg structures 13 when nested.

The outside perimeter of flange 18 preferably fits tight against the vertical side 16 of the annular recess 14. A tight fit transfers any sidewise loading of the leg structure 13 directly into the platform 11 avoiding shock loading of the attachment means.

Leg structures 13 are preferably bonded at the upper surface 22 of the flange 18 to the bottom surface 15 of the annular recess 14. If no mechanical locking device,

such as hardened staple 23, is employed to attach the bottom surface of flange 18 to platform 11, a very high strength bonding agent 24, such as well known epoxy resins, with or without fillers, is employed. If, however, the lower complementary platform 12 is used, a regular cheap commercial adhesive, similar to the adhesive bonding means 25, can be used.

The complementary platform 12 is usually made of the cheapest available materials generally available, as its main purpose is to keep the leg structure 13 from falling out of the supporting platform 11 when lifted free. Should some structural strength he required to overcome the tendency of the supporting platform 11 to bend between leg structures a stiff complementary platform will add stiffness.

Adhesive bonding means 25 is applied over the entire bottom surface of platform 11 and the complementary platform 12 secured in surface to surface contact thereto. Even though the platforms may be securely bonded in surface to surface contact, it has been found desirable to mechanically attach, as by staples 26, the platform 12 at the edges and/ or near the apertures to assure proper surface to surface drying of the adhesive and to prevent the platforms from being parted by heavy use.

In practice, platform 11 may be constructed from a laminated plywood, reinforced plastic board, bonded fiber or flake materials. Plywood presently is both cheaper and lighter where high strength is required. The apertures 17 are cut in the platforms 11, 12 with conventional saws. The annular recesses 14 are routed deep enough so that the flange 18 of the leg structure 13 leaves no bottom surface 27 exposed which could be caught by a prong of a fork lift truck. To assure that bottom surface 27 of the flange 18 is clear, the annular recesses are routed deeper than the thickness of the flange leaving a clearance 28.

Having explained the novel pallet structure it can be observed that the leg structure 13 of the pallet under load will not tend to break loose as it is trapped by a downward force in a recess. Even when struck by a prong of a fork lift truck the force on the leg structure 13 is transferred into the supporting platform 11. Thus, it is apparent that either a bonding agent 24, a staple 23, the complementary platform 12 or any combination of such means is capable of holding the leg structure 13 in place.

I claim:

1. A nestable pallet comprising:

an upper support platform,

a complementary lower retainer platform,

mating apertures in said platforms,

a plurality of cup-shaped leg structures each having a flange extending substantially horizontally outward from the top of the cup,

a truncated cone-shaped leg depending therefrom, and

a disk-shaped base closing the smallend of the cone,

annular recesses in the bottom surface of said upper platform surrounding said apertures,

said recesses being of excess sufficient depth to receive the flanges of the leg structures in shear restraint, and

adhesive bonding means securing the entire mating interfaces of said platforms in surface to surface contact.

2. A nestable pallet as set forth in claim 1, wherein the depth of the annular recesses is greater than the thickness of the flanges of the leg structures.

3. A nestable pallet as set forth in claim 2, wherein the top surface of the flanges of the leg structures is secured to the horizontal surfaces of the annular recesses by adhesive bonding means.

4. A nestable pallet as set forth in claim 1, which further includes mechanical fasteners connecting small isolated areas of said platforms adjacent said recesses.

5. A nestable pallet as set forth in claim 1, wherein leg structures are made of low carbon steel and the thickness of the truncated cone-shaped leg is less than the thickness of the flange.

6. A nestable pallet as set forth in claim 1, wherein the connection between the flange and the leg is formed on a radius between A and /2" and the taper of the truncated cone-shaped leg is between 14 and 30.

7. A nestable pallet comprising:

a pair of rectangular platforms each having a top surface and a bottom surface,

a plurality of mating apertures through said platforms,

a plurality of shallow shear restraining recesses in the bottom surface of the upper platform surrounding said apertures,

a plurality of leg support structures each having a flange extending substantially horizontally outward from the top of the leg structure and a truncated tapered leg depending therefrom,

the depth of said shear restraining recesses being slightly greater than the thickness of said flange of said leg structures so that when seated therein the bottom surface of the upper platform is below the bottom surface of the flange,

a first adhesive bonding agent securing the upper surface of the flange of the leg structures to the bottom surface of said recesses in horizontal shear restraint therewith, and

a second adhesive bond securing the entire mating surfaces of said platforms in face-to-face contact, whereby said recesses form a primary shear restraint and said first adhesive bonding agent forms a secondary shear restraint, the bottom platform providing a reinforcement to maintain said primary and said secondary shear restraints operative.

References Cited UNITED STATES PATENTS 2,544,657 3/ 1951 Cushman 108-53 2,706,099 4/ 1955 Whalley 10853 3,199,468 8/ 1965 Sullivan 108-53 3,220,681 11/1965 Erbert 248119 3,267,883 8/1966 Vissers 10853 FOREIGN PATENTS 795,564 5/1958 Great Britain. 337,125 4/1959 Switzerland.

JAMES T. MCCALL, Primary Examiner.

G. O. FINCH, Assistant Examiner. 

